chore(ci): isolate mise state in performance jobs

[jdx]

The delayed performance check on #814 fails before building fnox because mise-action cannot write /github/home/.local/share/mise/bin/mise. Removing the old executable leaves its parent directory unwritable. Failing run.

Give both performance workflows fresh mise data, cache, and state directories beneath RUNNER_TEMP, shared with subsequent steps through GITHUB_ENV. The pinned runner image, Rust toolchain, and benchmark commands stay the same.

Validation: Actionlint and ShellCheck pass for both workflows; the extracted setup step successfully creates and exports three writable directories. The self-hosted performance run needs to validate the full setup after merge because its trusted workflow comes from the default branch.

AI-assisted — Tool: Codex; model: OpenAI/GPT-6; version: unavailable.

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Note

Low Risk
CI-only workflow setup change; no application code, auth, or data paths affected.

Overview
Fixes self-hosted performance jobs failing when mise-action cannot write under the shared runner home (e.g. after removing a stale mise binary left directories owned by another user).

In perf.yml and perf-pr.yml, the sudo rm mise cleanup step is replaced with Prepare writable mise directories: a temp tree under RUNNER_TEMP and MISE_DATA_DIR, MISE_CACHE_DIR, and MISE_STATE_DIR appended to GITHUB_ENV so later steps (including jdx/mise-action) use isolated, writable state. Benchmark pinning, Rust toolchain, and measurement commands are unchanged.

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Summary by CodeRabbit

• Chores
  • Improved performance test workflow reliability by isolating temporary tool configuration and state for each run.
  • Removed cleanup of a shared runner-level tool installation.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository YAML (base), Central YAML (inherited), Organization UI (inherited)

Review profile: CHILL

Plan: Team

Run ID: cdd71ef9-b4ec-4659-82ec-eb419b37ec8e

📥 Commits

Reviewing files that changed from the base of the PR and between eb9f097 and b5a2c6a.

📒 Files selected for processing (2)

• .github/workflows/perf-pr.yml
• .github/workflows/perf.yml

Included review availability: Your plan provides up to 8 included reviews per hour; 3 remain after this review.

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📝 Walkthrough

Walkthrough

The performance workflows now create temporary writable mise directories under the runner temporary directory. They export the data, cache, and state paths through GITHUB_ENV and remove shared stale-binary cleanup.

Changes

Performance workflow isolation

Layer / File(s)	Summary
Configure isolated mise directories .github/workflows/perf-pr.yml, .github/workflows/perf.yml	The setup steps create temporary mise roots under $RUNNER_TEMP and export MISE_DATA_DIR, MISE_CACHE_DIR, and MISE_STATE_DIR. They no longer delete the runner-owned mise binary.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Merge Risk: ⚪ Minimal · up to b5a2c

Performance workflows now use per-job writable mise state rather than shared runner state, preventing the prior unwritable-directory failure without changing benchmark commands or toolchain configuration.

Poem

A rabbit reads each line,
The patch grows clear beneath the moon,
Small changes hop in place,
Tests guard the garden path,
Reviews bloom before the dawn.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: isolating mise state in performance CI jobs.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[greptile-apps]

Greptile Summary

The PR isolates mise data, cache, and state for both performance workflows in fresh per-job directories beneath RUNNER_TEMP.

• Replaces cleanup of the stale shared-home mise executable.
• Exports the isolated directories through GITHUB_ENV before invoking mise-action.
• Applies identical setup to pull-request and scheduled performance measurements.

Confidence Score: 5/5

The PR appears safe to merge; no actionable correctness, security, or repository-rule issues were identified.

The fresh mise root is created atomically, its directory variables persist to subsequent steps through GITHUB_ENV, and mise-action creates the required child directories and installs its binary under the overridden data directory.

Important Files Changed

Filename	Overview
.github/workflows/perf-pr.yml	Creates and exports isolated mise directories before the pull-request performance job installs and invokes mise.
.github/workflows/perf.yml	Creates and exports isolated mise directories before the recurring performance job installs and invokes mise.

_{Reviews (1): Last reviewed commit: "chore(ci): isolate mise state in perform..." | Re-trigger Greptile}